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Royal Society of Chemistry, Green Chemistry

DOI: 10.1039/c5gc03052h

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Recovery of an antidepressant from pharmaceutical wastes using ionic liquid-based aqueous biphasic systems

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

This work is aimed at developing a sustainable process for the recovery of valuable drugs from pharmaceutical wastes by using ionic liquid (IL)-based aqueous biphasic systems (ABS). Since in pharmaceutical wastes, excipients consist on the major contaminants, the search for selective routes for their elimination is of primordial relevance, and for that purpose, IL-based ABS were here evaluated. The effects of different process parameters, namely the IL nature, the pH and the mixture composition used in the extraction system were studied and the process optimized to maximize the extraction of the antidepressant from pharmaceutical wastes. Moreover, the maximum amount of amitriptyline able to be processed using such systems was assessed. The set of ABS investigated herein revealed high extraction performance, as indicated by the outstanding logarithmic functions of the amitriptilyne partition coefficients ranging from 2.41 ± 0.05 to >2.5 and extraction efficiencies between 66 ± 1 % to 100. The best ABS and conditions were considered in the development of an integrated multi-step purification process. The process here proposed comprises three main stages: the solid-liquid extraction of the antepressant from ADT 25 pills, its purification using the optimal IL-based ABS and the antidepressant isolation by precipitation with anti-solvent. After the removal of most water insoluble excipients in the first step, with the selected IL-based ABS it was possible to further eliminate water soluble contaminants. A high capability of extraction and purification, leading to the selective separation of amitriptyline hydrochloride from the main contaminants contained in solid pharmaceutical wastes was achieved. Finally, through precipitation with the anti-solvent the isolation of the amitriptilyne in a pure state was successfully accomplished.